The coloration of flames has been known for centuries. Typically, this is attained by the injection of color producing agents in some manner into the flame or incorporation of such agents in the fuel that produces the flame. Metallic salts have historically been used as flame coloration agents with the particular color generated being dependent primarily on the metal content of the salt. This chemical phenomenon has been used for ages in fireworks and, more recently, in color producing fireplace logs and kindling.
Also recently, the concept of adding color to flames generated by portable combustion devices, e.g. a pocket lighter for cigarettes, has been disclosed in U.S. Pat. No. 3,468,615.